MAX34565 [MAXIM]
12V Hot-Plug Switch in TDFN Package; 12V热插拔开关，采用TDFN封装
| 型号： | MAX34565 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 12V Hot-Plug Switch in TDFN Package |
| 文件： | 总10页 (文件大小：1223K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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19-6083; Rev 0; 12/11
General Description
Features
The MAX34565 is a hot-plug controller for 12V power
rails. It is a completely integrated solution including the
required power-pass MOSFET device for 12V supplies.
During hot-plug, the device controls the supply output
voltage ramp (dV/dt) and limits the current at a user-
controlled level. The device also limits the output voltage
to protect downstream devices from overvoltage events.
The MAX34565 is offered in a latchoff version.
SꢀCompletelyꢀIntegratedꢀHot-PlugꢀFunctionalityꢀforꢀ
12VꢀPowerꢀRails
SꢀOn-BoardꢀPowerꢀMOSFET
SꢀNoꢀHighꢀPowerꢀR ꢀResistorꢀNeeded
SENSE
SꢀAdjustableꢀCurrentꢀLimit
SꢀAdjustableꢀOutputꢀVoltageꢀSlewꢀRate
SꢀThermalꢀFaultꢀIndication
SꢀOutputꢀOvervoltageꢀLimiting
SꢀOn-BoardꢀThermalꢀProtection
SꢀOn-BoardꢀChargeꢀPump
SꢀLatchoffꢀVersion
Applications
®
RAID/Hard Drives
Servers
Switches/Routers
PCI/PCI Express
InfiniBandTM/SM
Base Stations
Ordering Information appears at end of data sheet.
Functional Diagram
V
CC
+12V
SUPPLY
68mΩ
5V
REG
CHARGE
PUMP
UVLO
LOAD
ILIM
+12V
LOAD
R
ILIM
CURRENT
LIMIT
OVERVOLTAGE
LIMIT
MAX34565
GND
VRAMP
C
VRAMP
V
OHT
17µA
EN/FAULT
1.4V
POR
BLANKING
V
OLT
THERMAL
LIMIT
THERMAL RESET
PCI Express is a registered service mark of PCI-SIG Corp.
InfiniBand is a trademark and service mark of InfiniBand Trade Association.
For related parts and recommended products to use with this part, refer to: www.maxim-ic.com/MAX34565.related
Forꢀpricing,ꢀdelivery,ꢀandꢀorderingꢀinformation,ꢀpleaseꢀcontactꢀMaximꢀDirectꢀatꢀ1-888-629-4642,ꢀ
orꢀvisitꢀMaxim’sꢀwebsiteꢀatꢀwww.maxim-ic.com.
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MAX34565
12V Hot-Plug Switch in TDFN Package
ABSOLUTEꢀMAXIMUMꢀRATINGS
(All voltages relative to GND.)
Voltage Range on V
12V Drain Current (T = +25NC, 0.5sq in. pad) .. 3.6A (continuous)
A
Continuous Power Dissipation (T = +70NC)
CC
A
Continuous.........................................................-0.3V to +18V
1ms ....................................................................-0.3V to +22V
TDFN (derate at 24.4mW/NC above +70NC)...........1951.2mW
Operating Junction Temperature..................... -40NC to +150NC
Storage Temperature Range .......................... -55NC to +150NC
Lead Temperature (soldering, 10s) ................................+300NC
Soldering Temperature (reflow) ......................................+260NC
Voltage Range on ILIM, VRAMP ..............-0.3V to (V
+ 0.3V),
CC
not to exceed +18V
Voltage on EN/FAULT .............................................-0.3V to +6V
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
RECOMMENDEDꢀOPERATINGꢀCONDITIONS
(T = -40NC to +150NC, unless otherwise noted.)
J
PARAMETER
Voltage
SYMBOL
CONDITIONS
MIN
9
TYP
MAX
13.2
30
UNITS
V
V
(Notes 1, 2)
12
V
CC
CC
R
Value
R
12
I
ILIM
ILIM
OLT
EN/FAULT Low Level (LOAD
Disabled)
V
0.80
V
V
EN/FAULT High Level (LOAD
Enabled)
V
3.3
OHT
ELECTRICALꢀCHARACTERISTICS
(V
= 12V, T = +25NC, unless otherwise noted.)
J
CC
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
1.6
8.0
7.0
1
MAX
2.25
8.5
UNITS
mA
V
Supply Current
I
(Note 3)
CC
UVLO Rising
V
7.5
6.5
UR
UVLO Falling
V
7.5
V
UF
UH
ON
UVLO Hysteresis
V
R
V
On-Resistance
68
88
mI
pF
NC
NC
V
MOSFET Output Capacitance
Shutdown Junction Temperature
Thermal Hysteresis
Overvoltage Clamp
C
400
+155
40
OUT
T
(Note 4)
+140
+175
SHDN
T
HYS
V
13.5
2.75
15
16.5
4.25
OVC
R
R
R
R
= 15.4I (Note 4)
3.44
2.1
4.6
3.5
7
A
Power-On Short-Circuit Current
Limit (Kelvin Sense)
ILIM
ILIM
ILIM
ILIM
I
SCL
= 24.9I
= 15.4I
= 24.9I
A
A
Operating Overload Current Limit
(Kelvin Sense)
I
OVL
A
C
C
C
= 270pF
ms
ms
ms
VRAMP
VRAMP
VRAMP
VRAMP Time
(0V to 12V)
t
= 470pF
12
VRAMP
= 1000pF
25
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MAX34565
12V Hot-Plug Switch in TDFN Package
ELECTRICALꢀCHARACTERISTICSꢀ(continued)
(V
= 12V, T = +25NC, unless otherwise noted.)
CC
J
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
EN/FAULT Fault Output Voltage
V
0.82
1.95
V
FAULT
Noteꢀ1: All voltages are referenced to ground. Currents entering the device are specified positive, and currents exiting the device
are negative.
Noteꢀ2: This supply range guarantees that the LOAD voltage is not clamped by the overvoltage limit.
Noteꢀ3: Supply current specified with no load on the LOAD pin.
Noteꢀ4: Guaranteed by design; not production tested.
Typical Operating Characteristics
(V
= 12V, T = +25°C, unless otherwise noted.)
J
CC
CURRENT LIMIT vs. TEMPERATURE
CURRENT LIMIT vs. TEMPERATURE
CURRENT LIMIT vs. R
ILIM
6
5
4
3
2
1
0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
6.0
R
= 15Ω
R
= 24Ω
ILIM
ILIM
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
I
OVL
I
OVL
I
OVL
I
SCL
I
I
SCL
SCL
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
12
15
18
21
(Ω)
24
27
30
R
ILIM
OVERVOLTAGE CLAMP vs. TEMPERATURE
ON-RESISTANCE vs. TEMPERATURE
SUPPLY CURRENT vs. TEMPERATURE
16.2
16.0
15.8
15.6
15.4
15.2
15.0
14.8
80
70
60
50
40
30
20
10
0
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
NO LOAD
10Ω LOAD
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
-40 -20
0
20 40 60 80 100 120
TEMPERATURE (°C)
����������������������������������������������������������������� ꢀMaxim Integrated Productsꢀ ꢀ 4
MAX34565
12V Hot-Plug Switch in TDFN Package
Typical Operating Characteristics (continued)
(V
= 12V, T = +25°C, unless otherwise noted.)
J
CC
TURN-ON WAVEFORMS
(V = 12V, EN/FAULT)
TURN-ON WAVEFORMS
(V = 12V, 10Ω RESISTIVE LOAD)
CC
CC
= 15Ω
MAX34565 toc07
MAX34565 toc08
R
ILIM
2V/div
V
CC
V
CC
2V/div
LOAD
LOAD
500mA/div
EN/FAULT
LOAD CURRENT
5ms/div
5ms/div
TURN-ON WAVEFORMS
(V = 12V, 3300µF CAPACITIVE LOAD)
CC
MAX34565 toc09
R
= 15Ω
ILIM
2V/div
V
CC
LOAD
LOAD CURRENT
1A/div
5ms/div
����������������������������������������������������������������� ꢀMaxim Integrated Productsꢀ ꢀ 5
MAX34565
12V Hot-Plug Switch in TDFN Package
Pin Configuration
TOP VIEW
LOAD LOAD LOAD LOAD LOAD
10
9
8
7
6
MAX34565
V
4
/EP
CC
+
1
2
3
5
GND VRAMP EN/ ILIM N.C.
FAULT
TDFN
(3mm x 3mm)
Pin Description
PIN
NAME
FUNCTION
1
GND
Ground Connection
Voltage Ramp Control. A capacitor connected to this pin determines the voltage ramp of the LOAD
output during turn-on according to the equation t = 25E6 x C for voltage ramp from 0
2
VRAMP
VRAMP
VRAMP
to 12V. This pin can be left open circuit for a minimum ramp time.
Enable/Fault. This pin is a multiple function digital input-output pin. When this pin is externally pulled
low, the MOSFET is turned off. When this pin is left open or not externally driven, the internal pullup
3
4
EN/FAULT reference pulls the input high, and the MOSFET is allowed to turn on. Note: Do not use an
external pullup on this pin. If the device experiences a thermal fault, this pin becomes an output that
is pulled internally to a mid-level voltage, V
.
FAULT
Supply Current Limit Adjust. A resistor from this pin to LOAD determines the current limit for the
pass connection.
ILIM
N.C.
5
6
No Connection. Do not connect any signal to this pin.
7
8
LOAD
Load Output. N-channel power MOSFET source connection.
9
10
12V Supply Input/Exposed Pad. Power-supply input and n-channel power MOSFET drain connec-
tion. Should be connected to a large trace or plane. The EP also acts as a heatsink, and can
dissipate heat from the device.
—
V
/EP
CC
����������������������������������������������������������������� ꢀMaxim Integrated Productsꢀ ꢀ 6
MAX34565
12V Hot-Plug Switch in TDFN Package
the device’s output is disabled. If the internal tem-
Detailed Description
perature of the device exceeds T
occurs and the device drives EN/FAULT to V
See Figure 1 for the EN/FAULT signal levels.
, a thermal fault
SHDN
.
The MAX34565 is a self-contained hot-plug switch
intended to be used on +12V power buses to limit
through current and to control the power-up output-
FAULT
An open-drain device should be connected to the EN/
FAULT pin for proper operation. Because the device
voltage ramp. The device begins to operate when V
CC
exceeds the undervoltage lockout level, V . At this
UR
pulls EN/FAULT to V
(a three-state condition) in the
FAULT
level, the enable circuit and EN/FAULT pin become
active. Once the device has been enabled by exceed-
on the EN/FAULT pin, a gate voltage is applied
to the power MOSFET, allowing current to begin flowing
from the V pad to LOAD.
event of thermal shutdown, this pin should not be con-
nected to an external pullup device. See Figure 2 for a
typical application circuit.
ing V
OLT
CC
The device contains an on-board 68mI n-channel power
MOSFET that is actively closed-loop controlled to ensure
that an adjustable current limit is not exceeded. The
maximum allowable current through the device is deter-
mined by an external resistor connected to the ILIM pin.
LOAD
ENABLED
THERMAL
SHUTDOWN/
FAULT
V
OHT
The device also contains the ability to control the power-
up output-voltage ramp. A capacitor connected to the
VRAMP pin sets the desired voltage ramp rate. The
output voltage is unconditionally clamped to keep input
overvoltage stresses from harming the load. The device
has an on-board temperature sensor with hysteresis.
If operating conditions cause the device to exceed an
internal thermal limit, the device unconditionally shuts
down and latches off while waiting for a power-on reset.
In the event of thermal shutdown, the device drives the
V
FAULT
LOAD
DISABLED
V
OLT
Figure 1. EN/FAULT Signal Levels
EN/FAULT pin to an intermediate voltage, V
.
FAULT
Undervoltage Lockout
CC
rising limit, V , must be exceeded before the MOSFET
UR
V
12V
CC
When voltage is applied to V , the undervoltage lockout
LOAD
circuit is enabled. When the voltage on V
drops below
CC
V
UF
, the current through the MOSFET is blocked. Note
MAX34565
that to allow current to pass through to the LOAD pins,
must exceed V and the voltage on EN/FAULT
R
V
CC
ILIM
UR
must exceed V
.
OHT
EN/FAULT
ILIM
Enable/Fault Function (EN/FAULT)
The EN/FAULT pin can be used to control the output
of the device and to indicate that a thermal fault has
occurred. The voltage level of the EN/FAULT pin is
compared to two internal sources: voltage on limit
VRAMP
GND
ENABLE
(V
) and voltage off limit (V
and the voltage level on EN/FAULT exceeds V
). When V
is above
OHT
OLT
CC
V
,
OHT
UR
the voltage ramp circuit turns on, enabling the device’s
output. When the voltage on EN/FAULT is below V
,
OLT
Figure 2. Typical Application Circuit
����������������������������������������������������������������� ꢀMaxim Integrated Productsꢀ ꢀ 7
MAX34565
12V Hot-Plug Switch in TDFN Package
Output-Voltage Ramp (VRAMP)
The voltage ramp circuit uses an operational amplifier to
control the gate bias of the n-channel power MOSFET.
Direct and Kelvin Current Sensing
The current limit circuit can be biased in one of two ways:
direct sensing or Kelvin sensing. Using direct sensing,
the sense resistor is connected between the ILIM pin and
the LOAD pins (Figure 3). Because the bond wires of all
five LOAD pins are in parallel, the on-resistance is slightly
lower. Using Kelvin sensing, only one of the LOAD pins
is connected to the ILIM pin through the sense resistor
(Figure 4). Using this circuit, the voltage on the die is
sensed, negating any impact of the bond wire resistance.
Because four LOAD pins are connected in parallel, the
on-resistance is slightly higher.
When the voltage on EN/FAULT is below V
, a FET
OLT
is used to keep C
discharged, which forces the
VRAMP
output voltage to GND. Once the voltage on EN/FAULT
is above V , an internal current source begins to
OHT
charge the external capacitor, C
, connected to the
VRAMP
VRAMP pin. The amplifier controls the gate of the power
MOSFET so that the LOAD output voltage divided by
two tracks the rising voltage level of C
. The output
VRAMP
voltage continues to ramp until it reaches either the input
level or the overvoltage clamp limits.
V
CC
Thermal Shutdown
The device enters a thermal shutdown state when the
temperature of the power MOSFET reaches or exceeds
Overvoltage Limit
The overvoltage-limiting clamp monitors the VRAMP
voltage level compared to an internal voltage reference.
T
, approximately +155NC. When T
is exceed-
SHDN
SHDN
When the voltage on VRAMP exceeds V /2, the gate
OVC
ed, the thermal-limiting circuitry disables the device
using the enable circuitry. The EN/FAULT pin is driven to
voltage of the n-channel power MOSFET is reduced,
limiting the voltage on LOAD to V even as V
V . The device is offered in two different versions:
OVC
CC
FAULT
increases. If the device is in overvoltage for an extended
period of time, the device may overheat and enter ther-
mal shutdown. This is caused by the power created by
the voltage drop across the power MOSFET and the load
current.
an autoretry version and a latchoff version.
I
LOAD
LOAD
LOAD
LOAD
LOAD
LOAD
TO APPLICATION
Current Limit
The load current is continuously monitored during the
MAX34565
initial voltage ramping (I
) and during normal opera-
SCL
tion (I
). If the current exceeds the current limit that is
OVL
R
LIM
set by the external resistance at ILIM, the gate voltage
of the power MOSFET is decreased, reducing the output
current to the set current limit. Current is limited by the
device comparing the voltage difference between the
LOAD and ILIM pins to an internal reference voltage.
When the output power is initially ramping up, the current
ILIM
Figure 3. Direct Sensing Circuit
I
limit is I
current limit is I
. Once the voltage ramping is complete, the
LOAD
SCL
. The lower I
OVL
current limit protects
LOAD
LOAD
LOAD
SCL
TO APPLICATION
the source if there is a dead short on initial power-up. If
the high current is maintained, the device will heat up
LOAD
LOAD
MAX34565
and the internal temperature will eventually reach T
.
SHDN
The device act as a fuse and automatically disable the
current flowing to the load when the temperature of the
power MOSFET has exceeded the shutdown junction
R
LIM
temperature, T
.
ILIM
SHDN
Figure 4. Kelvin Sensing Circuit
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MAX34565
12V Hot-Plug Switch in TDFN Package
Latchoff Version
Once the latchoff version has entered thermal shutdown,
it does not attempt to turn back on. The only way to turn
this device back on is to cycle the power to the device.
R
. To greatly reduce this offset, it is recommended
ILIM
that one of the LOAD pins have a dedicated connection
to ILIM though R , and not be used to pass the LOAD
current, I
ILIM
(Figure 6). This would leave four LOAD
, which should be sufficient. Because
LOAD
When power is reapplied ton the V
pad, the junction
for the device
pins to pass I
CC
LOAD
temperature needs to be less than T
to be enabled.
there is only a small amount of current passed from this
lone LOAD pin to ILIM, there is a negligible voltage offset
applied to the internal comparator. This method is the
SHDN
Applications Information
best way to attain an accurate current limit for I
.
LOAD
Exposed Pad (V
)
CC
The exposed pad is the voltage supply pin for the device
and should be connected to a large trace or plane. The
exposed pad also acts as a heatsink, and can dissipate
heat from the device.
V
CC
Decoupling Capacitors
It is of utmost importance to properly bypass the device’s
supply pins. A decoupling capacitor absorbs the energy
stored in the supply and board parasitic inductance when
the FET is turned off, thereby reducing the magnitude of
0.5µF
MINIMUM
REQUIRED
MAX34565
overshoot of V . This can be accomplished by using a
high-quality (low ESR, low ESL) ceramic capacitor sol-
CC
GND
dered directly between the V
and GND connections.
CC
2Ω TO 10Ω
RECOMMENDED
Any series resistance with this bypass capacitor lowers
its effectiveness and is not recommended. A minimum
0.5FF ceramic capacitor is required (Figure 4). However,
depending on the parasitic inductances present in the
end application, a larger capacitor could be necessary.
BOARD GROUND
Current Limiting Resistor
A small resistor (2I to 10I) in series with the GND pin of
the device limits current flow during momentary reverse
avalanche break down, and consequently limits total
parasitic charge injected into the device (Figure 5). If this
method is used, it is imperative that the bypass capaci-
Figure 5. Power Conditioning Circuit
TO APPLICATION
LOAD
LOAD
LOAD
tor be directly across chip V
and ground connections,
CC
LOAD
LOAD
MAX34565
though not through this resistor.
LOAD and ILIM Connections
Small parasitic resistances in the bond wires of the LOAD
pins and in the traces connected to the LOAD pins can
result in a voltage offset while current is flowing. Since
R
LIM
ILIM
the voltage drop across R
is used to set the I
and
ILIM
SCL
I
I
limits, this induced offset can increase the value of
OVL
SCL
Figure 6. LOAD and ILIM Connections
and I
from the specified values for any given
OVL
����������������������������������������������������������������� ꢀMaxim Integrated Productsꢀ ꢀ 9
MAX34565
12V Hot-Plug Switch in TDFN Package
Ordering Information
PART
MAX34565ETB+
MAX34565ETB+T
TEMPꢀRANGE
-40NC to +150NC
-40NC to +150NC
THERMALꢀSHUTDOWN
Latchoff
PIN-PACKAGE
10 TDFN-EP*
10 TDFN-EP*
Latchoff
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
*EP = Exposed pad.
Package Information
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages.ꢀNote that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains
to the package regardless of RoHS status.
PACKAGEꢀTYPE
PACKAGEꢀCODE
OUTLINEꢀNO.
21-0137
LANDꢀPATTERNꢀNO.
90-0061
10 TDFN-EP
T1033+2
MAX34565
12V Hot-Plug Switch in TDFN Package
Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
0
12/11
Initial release
—
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.
Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical
Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
10
©
2011 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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